Portable electronic devices such as cellular phones have been popular worldwide due to its portability and convenience as a communication device. Further, the functions of a cellular phone may incorporate features of many software packages (e.g., games, phone book, voice box, alarm, message transmission, etc.) to form a multi-functional cellular phone. Such provision of diversified services to consumers is the trend dominating the market. For example, in using phone book of cellular phone, user has to edit by manually inputting characters including alphabets and symbols in order to store frequently used telephone numbers or alphabets therein. Such stored telephone numbers or alphabets are for the facilitation of making a call later. Currently, the manual input is classified as either keypad input or touch screen input in which the former is the widely used one due to lower cost. It is also known that keypad (e.g., alphanumeric keypad) of cellular phone only comprises a small number of keys (e.g., 12 keys in one type of commercial available cellular phone). Hence, it is impossible that each of 26 English alphabets has a unique key on the keypad. In other words, a single key is configured to correspond to multiple alphabets or symbols. For example, numeric key “2” represents alphabets “ABC”, key “3” represents alphabets “DEF”, . . . , key “8” represents alphabets “TUV”, and key “9” represents alphabets “WXYZ”. Hence, user has to press a single key for more than one time for inputting a desired alphabet or symbol. For example, user may press key “2” twice for inputting alphabet “B”, key “6” three times for inputting alphabets “OO”, and key “5” twice for inputting alphabet “K”, thus completing input of word “BOOK”. In view of above, its input speed is very slow and it is inconvenient in use. This condition is even worse when user inputs many alphabets for sending via a cellular phone having capability of accessing the Internet. In addition, for example, in a commercially available cellular phone having intelligent input software, user can input one or more key alphabets of a word on keypad of the cellular phone. In response, the software can automatically search the corresponding word based on the key alphabet(s) prior to displaying the found word. This is an improvement with respect to speed as compared with above conventional technique. However, it still suffered from a disadvantage. That is, a key-in error of a word cannot be identified immediately for correction. For example, the intelligent input software is compromised when “telephone” is keyed in as “telefone”.
Additionally, there is another type of commercially available cellular phone having an externally coupled standard keypad having a sufficient number of keys. In use, user can couple the external keypad to his/her cellular phone for inputting alphabets including symbols therefrom. This is an improvement with respect to the prior art intelligent input software. However, it is well known that reasons for the increasing use of cellular phone are portability, compactness, and lightweight. Hence, the provision of external keypad (i.e., increasing weight of cellular phone) may compromise the advantages of cellular phone. Thus, this is impractical. In view of above, improvement still exists in order to overcome the above drawbacks of prior art.